Rotary expansive tool



July 16, 1929.

L. S. CAMPBELL ROTARY ExPANsIvE lrooL Filed Jan. 19, 1928 2 Sheets-Sheetl Mor/26g July 16, 1929- L.. s. CAMPBELL ROTARY EXPANSIVE TOOL 2Sheets-Sheet` 2 Filed Jan. 19. 1928 l Ml Patented kJuly 1e, 1929.

UNITED STATES/ PATENT oFFIC'E.

LAWRENCE S. CAMPBELL, F KANSAS CITY, MISSOURI, ASSIGNOR TO JOHN G'RANI,

, OF LOS lANGELES, CALIFORNIA.

ROTARY EXIIPANSIVE] TOOL.

Application led January 19, 1928. Serial No. 247,824.

This invention has to do with expansive well tools, and,'in the typicalembodiment heredescribed, with devices of the type generally known asexpansive reamers or underreamers, and particularly with rotaryunderreamers; the particular objects and accomplishments of theinvention `will perhaps be best understood from the subjoined specificdescription of a preferred embodiment of the invention; but I may statepreliminarily that among the various objects of the invention there isthe object of providing -a reamer which does not depend upon the actionof a spring for its expansion but is expanded by a positive movement,and is likewise contracted by positive movement. Also involved in theinvention, and adapted to the particular features of design which embodyother characteristics, is the feature of locking the cuttersl in theirinward `or contracted positions so that they may be prevented fromriding the pipe while the reamer is passing through the well pipe. Inthe characteristie typical design hereinafter explained' the structureand operation are such that, whenA the reamer passes below the well pipeand is to be expanded, positive rotation of the drill stem in arighthanded direction causes positive expansion of the reamer. Then whenit is desired to contract the reamer it is not necessary to rota-te thedrill pipe in the opposite direction, or left-handedly, but -it is onlynecessary to pull the reamer up against the bottom of the well pipe orwell pipe shoe ".3 when it will be immediately contracted. In thiscontracted position the cutters are held inwardly so that they do. notpress against the pipe, and the reamer maybe withdrawn from the`wel.Upon subsequent insertion the reamer may Y tracted condition in which ithas been withdrawn from the well, or it may be placed in what maybetermed its normal contracted condition; but as will be notedhereinafter, from either of its contracted conditions the reamer may bethrown to its expanded posi-v tion'by positive right handed rotationl ofthe drill stem.

In thesillustrative embodiment of the. invention hereinafter describedthere are many other characteristic features, such as the forvmation ofthe cutter carriers, and their engagement and vinteraction with theexpand- `the parts in the be either inserted in its conmay be eitherregarded as a mg cams, etc., but all of which will be best. understoodwhen the embodiment is consid-Y position, this section being taken asindicated by line 2-2 on Fig. 3;

Fig. 3 is a cross section on line 3-3 of Fig. 2;

-Fig 4 is a cross-section yon line 4.-4 of F ig.2; a

Fig. 5 is a section similar to that of Fig. 2.

this section being taken as indicated by line 5-5 on Fig. 6.

Fig. 6 is a cross-section on the line indicated 6*(5 on Fig. 5;

Fig. 7 is a vertical longitudinal section of the part-s showing them lin the contracted vposition they assume as they are drawn up through thepipe, this section being taken as indicated by line 7-7 on`Fig. 8;

Fig. 8 is a cross-section of the reamer taken as indicated by line 8 8on Fig. 7; and

Fig. 9 is asimilar cross-section showing position which they assume justbefore going back to the position shown in Figs. 2 and 3. In-the drawingthere is shown a reamer body 10 which for the purposes of the specificdesign herein delineated is made up of an uppenhead 11 and lower hea-d12 joined together longitudinally by connecting members 'or webs 13. Forpurposes of assembling and disassembling the particular design hereinshown these webs 13 may be releasably connected with one of the heads,as for instance by the screws or bolts 14, one of which is shown inFig. 1. The body as thus made up sort of cage with upper and lowerheads, or 'may be regarded as a slotted body (theslots lying betweenadjacent connecting webs 13) with an internal bore (the space inside thewebs 13). A mandrel is provided which extends longitudinally through thebody, bodiment is shown as made up ofrseveral interconnectedparts. Theupper mandrel portion 15 extends through upper head 11 and has at itsupper end the usual tapered and threadedl pin 16 for connection with adrill stem kas shown at 17. The middle mandrel portion 18 is the camcarrying part of the 'mandrel and it extends vertically between the andin this particular emtwo heads of the body, being screw-threaded at 19to the upper' mandrel portion. The lower mandrel portion 2O isscrew-threaded at 21 to the middle mandrel portion and has at its lowerend a screw-threaded box 22 to receive the threaded pin of a drill bit23. Although I have shown the mandrel thus as made up of three separateparts removably joined together, and although for some reasons it may bedesirable to thus construct the mandrel, the mandrel can be made in asingle piece; and as in operation it acts as a single member I shallhereinafter refer to this composite mandrel merely as the mandrel exceptwhere otherwise specifically stated.

Near its upper end the mandrel passes through a bore 25 in the uper endof upper head 11, in which bore the mandrel is both rotatable andlongitudinally movable; and near its lower end the mandrel has the samekind of bearing in the bore 26 of the lower head.

A coil spring 27, within upper head 11, nor-l mally presses the mandreldown, the lower end of this spring rests upon a mandrel shoulder whichmay conveniently be formed by a ring or washer 30 which surrounds themandrel and rests upon the upper faces of the uppermost cam members 32.These cam members are arranged in sets, and of the sets there may be anysuitable number, depending upon the number of cutters or cutter setsused in the reamer. In the particular design here shown I utilize threecutter sets and therefore three cutter carriers and three sets of cammembers. Likewise each set of cams (each of the vertical rows of cammembers 32) may contain any desired number of cam members, depending`upon the number of separate cutter carrying arms that is utilized ineach cutter carrier. From a consideration of the detailed description ofstructure and operation which follows it will be readily recognized thatmy invention may be applied to cutter' carriers which embody but asingle extendine` cutter carrying arm-in other words to cutter carriersAwhich are not furcated into a seriesof vertically spaced arms-or whichhave the vertically spaced recesses which the spaced arms specificallyprovide-or, as shown in the drawings, to cutter carriers having anydesired number of vertically spaced cutter carifving arms. One advantagein using cutter carriers with a plurality o f vertically spaced arms orvertically spaced recesses is, as will be understood from what follows,that the vertical movement of the mandrel and the cam members need notbe so large in order to move a cam member vertically from a positionwhere it is behind a cutter carrier or cutter carrying arm to a positionwhere it is above the carrier or carrier arm or in register with arecess. Another advantage ot using a cutter carrier divided into anumber of vertically spaced arms lies in the fact. that a number ofseparate cutter members, such as separate rollers, may be utilized, andthe roller mandrel given very solid support at closely spaced pointsalong its length. Each of the cutter carriers`35, in the specificembodiment shown in the drawings, is here shown as-a. swinging cuttercarrier. It will be recognized that the essential characteristics of thecutter carrier for this reamer require merely that the cutter carriersshall be movable inwardly and outwardly to and from the central axis ofthe reamer; and, broadly speaking, the cutter carriers can be mounted soas to move in any suitable manner. But for purposes of simplicity ofstructure and surety of action I choose to mount the cutter carrierspivotally to swing about their axis pins 36 which are loca-ted onvertical axis lines near one of the carrier edges. The opposite edgeportion of each carrier is divided into a number of vertically spacedarms 40 which allow sutlicient space between them for the inter-positionof roller cutters 41 mounted on mandrel pins 42 each of which preferablyextends vertically throughout the vertical length of a cutter carrier.Thus in the particular design here shown each mandrel pin 42 carriesthree roller cutters 41, and cach separate roller cutter 41 is thussupported on a mandrel pin which is supported immediately adjacent eachroller cutter by an arm of the carrier. And, as will later be seen, aseach Acarrier arm is directly supported from the interior by a cammember, the radial and circumferential thrust support of each rollercutter becomes very strong and direct, all

of the parts being put intodirect compressive Y l or shearing stressrather than having any bending stresses imposed upon them.

Located within the lower head 12 there is a cutter expanding sleeve 50which has a frustro conical head 51 pressed upwardly by a spring 52against extensions 53 which are provided'on the lower ends of cuttercarriers 35. The function of this sleeve and conical head, operated bythe rather light spring 52, is merely to press the cutter carrieroutwardly against the wall of the drill hole to insure sufiicientcontact of the cutters with the wall to retard rotation of the cuttersand the reamer body suticiently to give positive expanding action whenthe mandrel is rotated. However, because in the average case the cuttersand. also the cutter carriers are in more or less forcible engagementwith the wall of the hole when the tool is let down to the point wherereaming operations' are to begin, it may not be necessary to use thecutter expanding sleeve and head.

For the particular design here shown,l as I have said before, cammembers 32 are arranged in three sets, each set in this particularinstance comprising a vertical row of four vertically spaced cam members32. These cam members are so vertically spaced, as shown yin the variousviews, that in the posi'- r rotatively locked together.

tion of Fig. 2 and Fig. 5 the cam members are in horizontal planes'corresponding to the horizontal planes of the carrier arms 40; so thatwhen the mandrel and the cam members are rotated from the position ofFigs. 2 and 3'to the position of Figs. 5 and 6, the cam members aremoved around directly b'ehind the several carrier arms and, in theselast positions, directly support the outer swinging ends of the carrierarms. This action takes place with the mandrel and the cam members' intheir lowermost positions, the downward movement of the mandrel beinglimited bythe engagement of' collar 55 with the upper surface of upperhead 11, or

with an intermediate collar 56 which is placed above head 11.

In the positions shown in Figs. 2 and 3the cutter carriers arein theirinnermost positions and the cutters are retracted toward the centerofthe tool. By relative rotation of the mandrel right-handedly, lookingdown upon the tool, cam members 32 are thrown from the position of Fig.3 to the position of Fig. 6. During-this rotation the inwardly extendingnoses 40a of the carrier arms ride the cam faces 32a and are pressedoutwardly; and as the cam members come finally to the position of Fig.6.y the `noses of the cams move into the notches 40h of the carrierarms, so that the parts then interengage and interlock in the positionof Fig. 6. It will be noted that the notches 401 are so formed that thecams cannot be rotated further in a righthanded direction, the cam nosescoming up against the walls of the notches, and the cutter carriersbeing prevented from swinging further outwardly by reason of engagementof their lower ends at v58 with upstanding anges 59 on t-he lower bodyhead l2. Thus, upon continued right handed rotation of the mandrelthecutter carriers arelocked in their protracted or expanded positionsand the mandrel and cutter carriers and body are all And it will benoted also that the carrier notches 40h are so formed that inward thrustwhich would tend to swing the cutter carriers about their axis pins 36cannot force the cams back in a lefthanded direction and away from thecutter carriers. Consequently inthis described' position of the parts,all of the parts are etectively locked against relative movement by anystresses imposed upon them.

When itis desired to withdraw the reamer from the hole and upv throughthe well pi e l) backward (left-handed) rotation of the 1;ill stem isnot necessary in order to contract the cut-ters. It is only necessary topull the ream- -er up. until either the cutter carriers or the uppermostcutters come into contact with the lower edge of the pipe. Furtherupward movement of the drill stem will then cause -upward movementof themandrel with relation to the body and cutter carriers, comand 1ts cammembers up to the relative elevated position shown in Fig. 7. Spring 27is strong enough that it will normallysupport the weight of the wholetool and of the drill bit attached to its lower end and always keep theparts in the relative vertical position shown in Fig. 2 while drillingand reaming are in progress; but the spring may be compressed by pullingthe tool up against the lower end of the casing. the cam members 32 aremoved directly upwardly from their positions shown in Figs. 5 and 6,until they occupy the relative elevated positions shown in Figs. 7 and8'or alittle higher than shown there; t-he cam members being then abovetheir respective carrier arms and registering with the spaces betweencarrier arms, which spaces are'at least of as great vertical width asthe cam members.. The cam members having assumed this position thenfurther upward movement of the mandrel, and upward movement of the bodyand carriers with it will cause the carriers -to lswing inwardly byreason of engagement of'their upper beveled edges 35a with the lower-end of the casing. These upper beveled edges or corners 35":l extendalong a considerable length of the uppermost curved carrier arms 40 asis best showny in F ig. 1, so that a curved beveled edge of some lengthis presented to the lower end ofthe casing giving good and smoothcontact with the casing or its shoe and precluding any liability ofthe'carriers cutting into the casing and causing any binding by reasonof edge toedge riers are thus moved moving inwardly intermediate thespaced cam members 32 until the carriers and cut- `ters are contractedsuiiiciently to pass within the casing, as shown in Fig. 7. Then thespring L27 moves the the cam'members are moved down with a fairly heavypressure against and upon the upper faces of the carrier arms, as shownin the position of Figs. 7 and 8. The whole pressure of spring 27 isexerted in pressing the cam memberslown on-the carrier arms andthus theycarrier arms are held or locked in their inward contracted position formovement through the pipe. Although of course the carrier arms could bemoved outwardly by a suliicient force, there is no such force applied tothem while being moved through the pipe. In fact if any force is appliedto the carrier arms during such movementit will be an inward, force dueto the cutters or carriers coming in contact with s ome locally "smalleror inwardly deformed part ofthe l pipe, which would do nothing but forcethe carriers inwardly a corresponding distanceg 'and the carriersl wouldthen stay in that inward position and out of normal contact with i thepipe.. When the tool reachcsthe surface 1t may,

Then this occurs v parts relatively so that if desired, be subsequentlyput back through tions. It is not the spring which tends to exthe pipein/the condition shown in Figs.I 6 /pand the cutters.

and 7. In this condition the carriers and cutters are still lockedagainst pressing outwardly against the pipe. If reinserted in the wellin this condition then when the tool reaches the place where reamingoperations are to begin and the cutters are again in contact with theformation, relative right handed rotation of the mandrel and cams willmove the cams first from the position shown in Fig. 8 to the positionshown in Fig. 9. In the specific design herein shown the cams in thismovement will contact somewhat with the roller cutters il andtemporarily move the cutters and carriers outwardly while the cams passthe cutters to reach the position of Fig. 9; but that temporary outwardmovement is of no significance. lVhen the parts reach the relativepositions of Fig. 9 the cams are still resting upon the carrier arms 40and the arms and cutters are thus locked against outward or expansivemovement. And the parts may be, if desired, put into the position ofFig. 9

. before the reamer is lowered through the casing. In any case, righthanded rotation of the mandrel from the position of Fig. 9 will, asapparent from an inspection of that figure, immediately move the cammembers to the position of Fig. 3, the cam members then being out ofengagement with the cam arms, and spring 27 will then immediately movethe mandrel and the cam members relatively downwardly to the relativeposition of Fig. 2, the carriers and cutters being still contracted).And it may be noted thatthe partsmay be, if desired, put into this lastmentioned relative position before being lowered through the casing. Inthis position of Fig. 3 the carriers and cutters are not locked againstoutward expansive movement but are free to swing outwardly, or aremovedoutwardly under the light pressure of expanding spring 52, if thatspring is used. However, even in the last mentioned positions of theparts, and particularly `if spring 52 is not used, .the cutters will notforcibly ride the pipe on the way down. There is no spring action, or atleast no heavy spring action, act-ing in any one of the three collapsedpositions of the parts, to force the cutters outwardly and expandthem,`as is the. case in any usual underreamer.

In the average underreamer, where a spring is used, that spring has aconstant tendency to expand the cutters, andusually by a wedging actionwhich, if anything, is enhanced by y the relatively upward drag of` thecuttersvon the pipe as the tool is lowered through the pipe. But in myreamer the only function of the spring is to hold the parts in what mavbe termed their normal relative position of longitudinal movement and toprovide that force which locks the cutters against expansion when theyare in their contracted posi- From what has been said it will now bereadilyv understood how the reamer, when it is put vdown through thepipe in any one of its contracted positions, is thrown to its expanded.position by positive right-handed rotation of the drill stem, andwithout the use of any relative longitudinal movement; and how thecutters are contracted by the positive relative longitudinal movementcaused by drawing the tool up against the lower end of the casing, andhow when the cutters are thus contracted there is no force tending tomake theml press heavily against the pipe; and how the cutters are infact locked against outivard movement to press against the pipe'wall.

VI have described the present embodiment of my invention as anunderreamer; but the invention is applicable to expansive andcontractive tools used for other purposes. In fact the invention may beapplied to any expansive and contractive tool in which the operations ofexpansion and contraction, as herein described, are applicable ordesirable. For instance, the invention is particularly applicable'topipe or casing perforators or cutting off tools, and needs no furtherdescription to show how my expanding and contracting mechanism ispeculiarly useful as applied to devices for perforating or for cuttingoft' a well casing. For either-of such operations, only the substitutionofY suitable per- `forating or cutter carriers is necessary; and

form the desired service by virtue of continued rotation, and then becollapsed by merely being pulled upwardly. p

My invention is thus not limited to use in any specified tool, neitheris it limited by they specifically described details of structure andoperation asset forth in the foregoing specification for purposes ofclarity of description; but on the other hand it is only to be v limitedas expressed in the following claims, which are to be construed in theirbroad and ninclusive senses as well as in their restricted senses asliterally expressed.

Although, for purposes of description, I have described the mandrel asbeing longitudinally .movable within the body, withouty or with relationto the body, itis understood that this mode of description of the mecha-'rotative movements, especially when the tool 'isfin the hole, thoserotative movements may mandrel movement in the operation of col-llapsing the cutters-that is, when the mandrel is moved upwardly relativeto the cutters so that the cutters then drop inwardly undei` themandrelcams. And even in that case, it is proper to view that relativemovementas a downward movement of the cutters on the mandrel rather than anupward movement of the mandrel with relation to the cutters. The viewthat the mandrel moves up between the cutters has, in this specificationand the following claims,

ed because of the fact, in the specific embodiment of the inventionherein described, 'that relative longitudinal movement is the movementthat contracts the cutters. In the following relative upward movement ofthe cutters with relation to the mandrel, which is'` caused by thespring 27, it is more proper to view thatrelative movement as being anupward relative movement of the cutters on the mandrel, rather than thedownward movement of)the mandrel between the Cutters.

The mandrel is mounted upon the drill stemand the spring cannot move themandrel and drill stem, but can only move the body and cutters.

I daim; 1. In an expanding tool of the character described, thecombination of a body, a cutter carrier mounted on the body to movelateralin the body movable` ly thereof, a mandrel both rotatively andilongitudinallywith relation to the cutter carrier, and a cam on themandrel' adapted to engage and move the cutter carrier by virtueofrotation and to be vmoved out of engagement with the cutter car` rierby virtue of relative longitudinal movement. p c

2. In anexpanding tool of the character described, the combination of abody, a cutter carrier mounted on the body to move laterally thereof,and a mandrel mounted in the body for longitudinal movement along androtative movement about the longitudinal axis, and a cain on the mandreladapted to engage and operate the cutter carrier in one longitudinalposition of the mandrel and to be out of engagement with the carrier inanother longitudinal position of the mandrel. I 3. In an expanding toolof the character described, the combination of a body, a cutter carriermounted on the body to move laterally thereof, a rotary andlongitudinally movbeen largely adoptand adapted by able mandrel withinthe body, a cutter carrier operating cam on the mandrel located behindthe cutter carrier in one longitudinal position of the mandrel andramand located out of register withk the cutter carrier in anotherlongitudinal position of the cam.

4. In an expanding tool of the character described, the combination of abody, a cutter carrier mounted on the body to move laterally thereof, arotative and longitudinally movable mandrel within the body, a cam onthe mandrel adapted by rotation when in one longitudinal position toengage the inner face of the cutter carrier and move the cutter carrieroutwardly, stop means on the cutter carrier limiting such rotativemovement of the cam to the a carrier is moved outwardly, and the cambeing movable out of engagement with the cutter carrier. by longitudinalmovement of the mandrel and cam.

In an expanding tool of the character described, the combination of abody, a cutposition in which the cutter ter carrier mounted on the bodyto move laterally thereof, a rotative and longitudinally movable mandrelwithin' the body, a cam on the mandrel adapted by rotation when in onelongitudinal position to engage the inner face of the cutter carrier andmove the cuttericarrien outwardly, stop means on the cutter carrierlimiting such rotative movement of the cam to the position in which lthecutter carrier is moved outwardly, and the cam being movableout ofengagement with the cutter carrier by longitudinal movement of themandrel and cam, the cutter carrier' being movable inwardly when the camis so moved longitudinally, and a spring tending to move the mandrellongitudinally to engage the cam endwise against the cuttercarrier tohold it in its inward position.

6. In an expanding tool of the character described, the combination of abody, a cutter carrier mounted on the body to move laterally thereof, arotative and longitudinally movable' means adapted by rotative movementto move the cutter carrier ,outwardly longitudinal movement to engagethe cutter carrier to hold it in inward. position. Y

7. In an expanding tool `of the character described, the combination ofa body, a cutter carrier mounted on the body to move laterally thereof,a mandrel in the body rotata-l ble about and movable along alongitudinal axis between two positions, a cam on the mandrel locatedbehind the cutter carrier in one of said longitudinal positions of themandrel andadapted in that position to move the rier and its stop meansfor further rotative movement out ot engagement with the carrier, and aspring acting between the cutter carrier and the mandrel to causemovementy of the parts back to their irst mentioned relativelongitudinal positions when the cam is rotated out of engagement withthe carrier.

8. In an expanding tool of the character described, the combination of abody adapted to be rotated about a vertical axis, a mandrel mounted inthe body for rotation relative thereto about a vertical axis and alsofor movement vertically Vwith relation to t-he body between a lowerposition and an upper position, a cutter carrier on the body andVmovable horizontally with relation thereto,

and a carrier operatingr cam on the mandrel positioned in the horizontalplane of the carrier when the mandrel is in its lower position andadapted to be raised Aabove the carrier when the mandrel is moved to itsupper' position.

9. In an expanding tool `of the character described, the combination ofa body adapted to be rotated about a vertical axis,-a mandrel mounted inthe bodyifor rotation relative thereto about a vertical axis and yalsofor movement vertically with relation to the body between a lowerposition and an upper position, a cutter carrier on the body and movablehorizontally with relation thereto, and a carrier operating cam on themandrel positioned in the horizontal plane of the carrierwhen themandrel is in its lower position and adapted to be raised above thecarrier when the mandrel is moved to its upper position, the carrierbeing movable to a position under the cam when the cam is in its upperposition. c

10. In an expanding tool of the character described, the combination ofa body adapted to be rotated about a vertical axis, a mandrel mounted inthe body or'rotation relative 4thereto about a vertical axis andalso-for movement vertically with relation to the body between a lowerposition and an upper position, a .cutter carrier on the body andmovable horizontally with relation thereto, and a carrier operatingcamon the mandrel positioned in the horizontal plane of the carrier whenthe mandrel is in its lower position and adapted to be raised above-thecarrier when themandrel is moved to its upper position, the carrierbeing movable to a position lunder the cam when thecam 1s 1n its upperwardly to and from the body, and a cam member within the body rotatableabout and movable vertically Valong a-,vertical axis and adapted in onevertical position to engage and movethe swinging carrier and in anothervertical position to be out of engagement with the swinging carrier.

13. In an expanding tool of the character described, the combination ofa body rotatable about a central vertical axis, a swinging cuttercarrier lmounted at one edge on a vertical axis on the body and havingits free end adapted to swing inwardly and outwardly to and from thebody, said swinging carrier having on its inner face toward the body aseries of vertically spaced recesses, a mandrel mounted in the body androtatable about and movable vertically along the axis ofthe body, andaseries of vertically spaced cams on the mandrel whose spacingcorresponds with the spacing of said receses.

14. In an expanding tool of the character described, the combination ofa body rotatable about a central vertical axis, a swinging-cuttercarrier mounted at one edge on a vertical axis on the body and havingits free end adapted to swing inwardly and outwardly to and from thebody, the swinging end of said carrier being divided into a plurality ofvertically spaced lingers, cutters carried at the swinging end of thecarrier in the spaces between lingers, a mandrel in the body rotatableupon and vertically movable along the axis of the body, a spring tendingto move the mandrel downwardly relative to the body, and a series ofvertically spaced cam members on the mandrel and whose vertical spacingcorresponds to the vertical spacing of said carrier fingers, so that inone vertical position of the mandrel the cam members are in horizontalregistration with said ingers and in another position of the mandrelsaid cam members are in horizontal registration with the spaces betweensaid fingers. f

15. In an expanding tool of the character described, the combination ofa body, a cutter carrier mounted on the body to move laterally thereof,a rotatable cam mounted in the body and adaptedto engage the carrier andmove it laterally outwardly away from the body, the carrier having a camreceiving notch into which the cam enters, said notch y lation to themandrel and engagement with thecam serving to prevent further rotationof the cam and to prevent backward cam rotation by virtue of inwardpressure exerted upon said carrier.

16. In an expanding tool of the character described, a mandreladaptedfor attachment toa drill stem, a cutter carrying cage, a cuttercarrier in the cage and movable in and out to andfrom the mandrel, thecutter carrier`being1movable longitudinallywith rethe mandrel beingrotative with relation to cam on the mandrel adapted to engage thecarrier in one longitudinal position and to -be out of such engagementin another longitudinal position.

17. In an expanding tool of the character described, a mandrel adaptedfor attachment to a drill stem, a cutter carrying cage, a cutter carrierin the cage-and movable in and out to and from the mandrel, the cuttercarrier being movable longitudinally withrelation to the mandrel and themandrel being rotative with relation to the carrier, a cam on themandrel adapted to engage the carrier in one longitudinal position andto be yout of such engagement in another longitudinal position, andyielding means to move the cutter longitudinallywith relation to themandrel.

v18. In an expanding tool of the character described, a vmandrel adaptedfor attachment to a drill stem, a cut-ter carrying cage, a cuttercarrier in the cage and movable in and out to and from themandrel, thecutter carrier being movable longitudinally with relation to the mandrelandthe mandrel being rotative with relation to the carrier, a cam on themandrel adapted*v to engage the carrier in one longitudinal position andto be outv of such engagement in another longitudinal position, and stopmeans on the carrier adapted to limit'relative rotation of the cam whenthe cutters are in their relative longitudinal position for camengagement.

19. In an expanding tool of the character described, a mandrel adaptedfor attachment -to a drill stem, a cutter carrying cage, acutter carriermounted on the cage and movablev in and out to and'from the mandrel, thecutter carrier being movable longitudinally with relation to the mandreland the mandrel being rotative with relation to the carrier, the mandrelhaving a formation adapted by rotatlve movement to move the carrieroutwardly andl adapted by longitudinal movement toengage vthe carrierand hold it in inward positlon.

20. In an expanding tool of the character described, a mandrel adaptedfor attachment to a drill stem, a cutter carrying cage, acutter carriermounted on they cage and movable in and out to' and from the mandrel,the cut- 7ter carrier being movable longitudinally with relation to themandrel andl the mandrel being rotative with relationto the carrier,

the carrier, and a rier being also movable eccentric face formed on saidthe mandrel having a longitudinally facing shoulder adapted to beselectively moved into and out of carrier engaging position by relativerotation.

2l. In an expanding tool of the character described, a mandrel adaptedfor attachment to a drill stem, a cutter carrying cage, a cutter carriermounted on the cage and movable in and out to and from the mandrel, thecutter carrier being movable longitudinally with relation to the mandreland the mandrel being rotative with relation to the carrier, the mandrelhaving a longitudinally facing shoulder adapted to be selectively movedinto and out of carrier engaging position by relative rotation, andyielding means moving the carrier longitudinally relative to the mandrclin a direction to move the carrier against saidA shoulder.

22. In an underreamer, a cage, a cutter carrier mounted in the cage andmovable in and out, a. mandrel extending through said cageand mountedfor rot-ary movement relative thereto, said mandrel being provided witheccentric shoulders for engagement with the inner edge of the cuttercarrier, and a shoulder formed on said mandrel beneath which the carrieris adapted to engage when in its inward retracted position.

23. In an underreamer, a cage, a cutter carrier mounted in the cage andmovable in and` out, a mandrel extending through said cage and mountedfor rotary movement relative thereto,

said mandrel being provided with eccentric shoulders for engagement withthe inner edge of the cutter carrier, a downwardly facing shoulderformed on said mandrel beneath which the cutter carrier is adapted toengage when in inward retracted position, and yielding pressure meansfor normally exerting upward pressure against said carrier.

24. In an underreamer, a cutter carrying cage, a cutter carrier mountedin the cage and arranged to move in and out therein, a mandrelassociatedwith said cage, the cutter carvertically longitudinally withthe reference to said mandrel, an mandrel for en-` gagement with theinner edge of said carrier, and means on said mandrel and carrier forlocking the latter against vertical longitudinal movement when inits'inner retracted position.

v 25. In an underreamer, a cutter carrying cage, a cutter carriermounted in the cage and arranged to move in and out therein, a mandrelassociated withsaid cage, the cutter carrier being also movablevertically longitudinally with) reference to said mandrel, an eccentricface `formed, on said mandrel for engagement with the inner edge of saidcarrier, means on said mandrel and carrier for locking the latteragainst vertical longitudinal movement when in its inner retractedposition, and yielding pressure means arranged within said cage beneathsaid carrier.

26. In an underreamer, a cutter carrying cage, a cutter carrier mountedin the cage and movable inwardly and outwardly therein, a mandrelextending into said cage and arranged to rotate therein, thecutter-carrier being also movable longitudinally with rela.- tion tosaid mandrel, means on said mandrel for engaging and projecting thecutter carrier when said mandrel is rotated, and means on said mandreland carrier for locking the latter in its inward retracted position.

27. In an underreamer, a cutter carrying cage, a cutter carrier mountedin the cage and movable ,inwardly and outwardly therein, a'

mandrel extending into said cage and arranged to rotate therein, thecutter-carrier being also movable longitudinally with relation to saidmandrel, and means on said mane drel and carrier whereby the latter isprojected upon relative rotary movement of said mandrel and wherebysaidcarrier is locked Y against vertical longitudinalvmovemcnt whenretracted. Y

28. In an expanding tool of the character described, a mandrel adaptedfor attachment to a drill stem, a cutter carrying cage, a cutter carriermounted on the cage and movable in and out to and from the mandrel, thecutter carrier being movable longitudinally with relation to the mandreland the mandrel being rotative with relation to the carrier, the mandrelhaving a formation adapted to move the carrier outwardly by virtue ofrelative movement between the mandrel and carrier, and the mandrel alsohaving a longitudinal facing shoulder adapted to be selectively movedinto and out of carrier engaging position by relative rotation.

29. In an expanding tool of the character described, the combination ofa cutter carrying body, a cutter carrier mounted on the body to movelaterally thereof, a rotatable cam mounted in the body and adapted byrotation relative to the carrier to move the carrier outwardly, andyielding means tending to move the carrier outwardly.

v30. In an expanding tool of the character described, the combination ofa cutter carry- 4,

ing body, a cutter carrier mounted on the body to move laterallythereof, a rotatable cam mounted in the body and adapted by rotationrelative to the carrier to move the carrier outwardly, and yieldingmeans independent of the cam acting to move the carrier outwardly.

In witness that I claim the foregoing I have hereunto subscribed my namethis 17th day of January, 1928.

LAWRENCE S. CAMPBELL.

